Access or Compose object using string literal. ex: '1.2.3' => {"1": {"2": {"3": "0"}}}

accessObject.js

'use strict';

const state = {
    a: {
        aa: {
            aaa: 'AAA'
        },
        ab: {
            aab: 'AAB'
        }
    }
};

function accessObject(context, properties, value) {
    properties = properties.split('.');
    let head = context;
    context = head;
    for (let i = 0; i < properties.length; i++) {
        if (i === properties.length - 1) {
            context[properties[i]] = value;
            break;
        }
        context = context[properties[i]];
    }
    return head;
}

function composeObject(properties, value) {
    properties = properties.split('.');
    let head = {};
    let context = head;
    for (let i = 0; i < properties.length; i++) {
        if (i === properties.length - 1) {
            context[properties[i]] = value;
            break;
        }
        context = context[properties[i]] = {};
    }
    return head;
}

const result1 = accessObject(state, 'a.aa.aaa', 'foo');
const result2 = composeObject('a.aa.aaa', 'foo');

console.log(JSON.stringify(result1, null, 1));
console.log(JSON.stringify(result2, null, 1));